Gold nanomaterials for the selective capturing and SERS diagnosis of toxins in aqueous and biological fluids

Abstract

A highly sensitive nanosensing method for the combined selective capture and SERS detection of Microcystin-LR (MC-LR) in blood plasma has been developed. The new method utilizes gold coated magnetic nanoparticles that are functionalized with anti MC-LR antibody Fab' fragments for the selective capture of MC-LR from aqueous media and blood plasma. Using an oriented immobilization approach, the Fab' fragments are covalently attached to gold surface to form a monolayer with high capture efficiency towards the toxin. After the selective capture, the purified MC-LR molecules were released from the extractor nanoparticles within 5min by manipulating the pH environment of the nanoparticles. The regenerated extractor nanoparticles maintained their capture efficiency and, therefore, were re-used to capture of MC-LR from successive samples. The released purified toxin was screened within 10min on gold coated silicon nanopillars and a new paper-based SERS substrate by handheld Raman spectrometer. The SERS enhancement factors of the nanopillars and the new paper-based substrate were 2.5×10 and 3×10 respectively. The lower limit of quantification (LOQ) of MC-LR by SERS on the nanopillar substrate was 10fM (R=0.9975) which is well below the clinically required detection limit of the toxin. The SERS determination of MC-LR was cross validated against ELISA. By using antibody fragments that are specific to the target biomolecule, the new methodology can be extended to the rapid extraction and detection of other toxins and proteins.

Thread based electrofluidic platform for direct metabolite analysis in complex samples

“…However, in most applications involving complex samples, e.g. biological samples, such as blood, sweat or urine, the separation of the target solute(s) from interferences within the matrix is required [43][44][45][46][47].…”

Waste-Derived Nanoparticles: Synthesis Approaches, Environmental Applications, and Sustainability Considerations

“…Researchers also utilize methods to reuse nanoparticles. For example, functionalized nanoparticles were successfully recycled to capture toxins from spiked blood plasma samples by applying a glycine buffer to free up the nanoparticles after their initial use (Hassanain et al, 2017 ). In another study, zinc oxide (ZnO) nanoparticles were synthesized from spent Zn-C battery via thermal technique at 900°C under an argon atmosphere using a horizontal quartz tube furnace.…”

Impedance Biosensing atop MoS2 Thin Films with Mo−S Bond Formation to Antibody Fragments Created by Disulphide Bond Reduction

“…Antibody fragments for detection of 3-phenoxybenzoic acid (3-PBA) were created by disulphide bond (SÀS) reduction in the hinge region of the antibody, which creates two antibody fragments with free sulfhydryl groups (ÀSH). Here tris(2-carboxyethyl)phosphine (TCEP) is utilized as the reducing agent [34,35], and disulphide bond reduction is accomplished by adding 10 mL of 5 mM tris TCEP to 1.0 ml of 10 mg/mL polyclonal 3-PBA antibody. This procedure is performed in the already assembled electrochemical cell with MoS 2 or CuÀMoS 2 coated onto GCE as the working electrode, and antibody fragment film formation is allowed to proceed for 3.0 h. The last step in biomolecular film formation is immersion into 0.1 % IgG-free BSA for 1.0 h to block sites that might be active towards non-specific adsorption.…”